package android.wheel.wheel.adapter;

import android.database.DataSetObserver;
import android.view.View;
import android.view.ViewGroup;

/**
 * Wheel items adapter interface
 */
public interface WheelViewAdapter {
        /**
         * Gets items count
         * @return the count of wheel items
         */
        public int getItemsCount();
        
        /**
         * Get a View that displays the data at the specified position in the data set
         * 
         * @param index the item index
         * @param convertView the old view to reuse if possible
         * @param parent the parent that this view will eventually be attached to
         * @return the wheel item View
         */
        public View getItem(int index, View convertView, ViewGroup parent);

        /**
         * Get a View that displays an empty wheel item placed before the first or after
         * the last wheel item.
         * 
         * @param convertView the old view to reuse if possible
     * @param parent the parent that this view will eventually be attached to
         * @return the empty item View
         */
        public View getEmptyItem(View convertView, ViewGroup parent);
        
        /**
         * Register an observer that is called when changes happen to the data used by this adapter.
         * @param observer the observer to be registered
         */
        public void registerDataSetObserver(DataSetObserver observer);
        
        /**
         * Unregister an observer that has previously been registered
         * @param observer the observer to be unregistered
         */
        void unregisterDataSetObserver(DataSetObserver observer);
}
